Packet Assembler-Disassemblers

There were also changes on the national telecommunications (telecomms) scene. The Post Office had developed an experimental packet-switched system for data transmission, known therefore as EPSS, which became available in 1975. With the development of Packet Assembler-Disassemblers (PADs), the existing ad hoc system of networking became somewhat more organised, and started to use standard protocols. Intramural communications also tended to become packet based. 

Remember that packets are specially structured groups of data, which include control and address information in addition to the data itself These packets must be assembled (control and address information added to data) somewhere before entry into the packet switched network and must be subsequently disassembled before delivery of the data to the message destination. This packet assembly and disassembly is done by a device known as a packet assembler/disassembler (PAD). PADs maybe stand-alone devices or may be integrated into modems or multiplexers. 

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